WASHINGTON — Far out on the Pacific Ocean, the world's industrial fishing fleets pursue one of the last huge wild hunts — for the tuna eaten by millions of people around the world.
Yet tuna still aren't fished sustainably, something that conservationists and big U.S. tuna companies are trying to fix. This illustrates one part of the pressure on the world's oceans to feed a growing global population, now 7 billion. It also underscores the difficulties people have in balancing what they take against what must be left in order to have enough supplies of healthy wild fish.
"It's serious. On a global basis, we've pretty much found all the fish we're going to find," said Mike Hirshfield, chief scientist at the advocacy group Oceana. "There's not a lot of hidden fish out there. And we're still heading in the wrong direction, taken as a whole."
Some 32 percent of the world's fish are overfished, up from 10 percent in the 1970s and 25 percent in the early 1990s, according to the United Nations Food and Agriculture Organization.
In the U.S., restrictions on fishing have allowed some fish populations to rebound. In international waters, however, covering more than half of the oceans, no single country oversees ocean conservation.
Instead, regional multinational organizations make the decisions. The first began after World War II, when their job was seen as dividing up what was then thought to be the unlimited wealth of the seas, said Amanda Nickson, who oversees Pacific tuna conservation efforts at the Pew Environment Group.
Today, Nickson said, these management groups aren't doing a very good job of restoring tuna populations and making sure they can be fished sustainability.
One of them is the Western and Central Pacific Fisheries Commission, which oversees more than 60 percent of the world's tuna catch. Its members include Pacific island nations and the homes of the world's large industrial fishing fleets — the U.S., Europe, Japan, China and Taiwan.
Nickson said it's a David vs. Goliath matchup of island nations pushing for sustainable management vs. the large fishing nations, which block the restrictions needed to achieve it. The group's next meeting is in December in the island nation of Palau.
The Pew Environment Group is pressing it to set limits on the amount of fish caught for each species; to take action to protect sharks, which are unintentionally caught along with tuna; and to reduce the catch of juvenile bigeye tuna, an overfished species, by ships fishing for skipjack tuna.
Skipjack, the most common tropical tuna, is very heavily fished in some places, but isn't yet overfished, said William Fox, a biologist and the World Wildlife Fund's U.S. vice president for fisheries. Skipjack is the only tuna species that hasn't been fished to its maximum limit or overfished, according to the United Nations Food and Agriculture Organization.
"We're in a race with time, because we're trying to get the regional fisheries management organizations to improve performance so that doesn't happen," Fox said. He's also vice chairman of the International Seafood Sustainability Foundation, a group started by the WWF with major U.S. tuna companies to try to make tuna fishing sustainable.
For U.S. fishing fleets, President George W. Bush signed a law in 2007 that required annual catch limits based on science in order to end overfishing by 2011. The limits were in place by the end of last year.
"We presume those catch limits — they're scientifically set — have ended overfishing, but we have to verify it, and we won't declare an end of overfishing until the scientific assessment is complete," said Eric Schwaab, director of the National Marine Fisheries Service.
However, limits and management are only part of the picture, Schwaab said. Damage to habitat along the coasts and in the ocean "probably will continue to challenge our ability to ultimately rebuild stocks to their historic levels," he said. "Also, there will be interactions among different species that are competing for space or for prey. ... We're going to continue to monitor, to study, and then make adjustments."
Better management globally would increase wild harvests, but not enough to meet the increasing demand for seafood, Schwaab said. Instead, the world is relying more on fish farming. Environmental groups are concerned that this will require more fish from the sea for feed.
Michael Rubino, who manages the aquaculture program at the National Oceanic and Atmospheric Administration, said the world supply of fish for such feed has held constant for the past 20 years, while aquaculture has grown. As a result, fish meal and fish oil have doubled in price in five years.
One fish used for aquaculture feed is menhaden. More menhaden are caught by weight than any other fish in the U.S. except Alaskan pollack. Much of it gets ground up as meal to feed farmed salmon and tuna. It's also fed to farm animals and cats, made into fertilizer and fish-oil capsules, and used as bait by sport fishermen.
For decades, menhaden has been fished up and down the Atlantic Coast with no limits except in the Chesapeake Bay. Stock assessments found no overfishing. Last spring, however, scientists recalculated and concluded that declining stocks appeared worrisome.
Charter owner Terry Gibson of Jensen Beach, Fla., said he's seen much less menhaden than his grandfather and father described. Menhaden feed marine mammals, birds and commercial and recreational fish, including striped bass.
Striped bass collapsed from overfishing in the 1980s.
"Many businesses like mine went bankrupt," Gibson said.
Controls were put in place, and now the striped bass numbers are considered healthy. Gibson and other recreational fishermen want to see menhaden stocks restored to feed them.
The Atlantic States Fisheries Commission decided on Wednesday to require leaving more menhaden in the water so their numbers can increase. It will decide on specific fishing restrictions next year.
Meanwhile, Oceana said in a report this month that better conservation is needed for the small fish at the bottom of the food chain on the West Coast, such as Pacific sardines. With world demand for wild-caught fish growing to feed the aquaculture industry, "it is imperative to take action today to avert a crisis tomorrow," the report said.
Regulation can work. Hirshfield, the Oceana scientist, said restrictions on fisheries have helped rebuild commercial fish stocks on both coasts. Haddock have been increasing since 2004. Summer flounder stocks are expected to be rebuilt in two years and are no longer considered overfished.
"What we're seeing, with a lot of pain and unhappy fishermen, is that the situation can be turned around," Hirshfield said. "We're seeing increasing populations of fish and therefore increasing catches in areas where overfishing had been chronic."
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